KR20090020983A - Method of preparing multi-layered inorganic electroluminescence device and multi-layered inorganic electroluminescence device prepared thereby - Google Patents

Abstract

A method for manufacturing a multi-layered inorganic electroluminescent device and a multi-layered inorganic electroluminescent device manufactured by the method are provided to increase brightness of the electroluminescent device while simplifying overall processes and reducing manufacturing cost. A lower electrode is formed on a substrate(1). A light emitting layer and a dielectric layer are simultaneously formed on the lower electrode by using a spin coating method(2). The step 1 and 2 are repeatedly performed several times on the dielectric layer and a plurality of complex layers including a lower electrode, a light emitting layer and a dielectric layer(3). A rear electrode is formed on an upper portion of the complex layer which is the most top layer among the complex layers(4).

Description

Method of preparing multi-layered inorganic electroluminescent device, and multi-layered inorganic electroluminescent device manufactured therefrom {Method of Preparing Multi-layered Inorganic Electroluminescence Device and Multi-layered Inorganic Electroluminescence Device Prepared Thereby}

Embodiments of the present invention relate to a method of manufacturing a multilayered inorganic electroluminescent device and a multilayered inorganic electroluminescent device manufactured therefrom, and more particularly, to provide high luminance light emitting characteristics using a multilayered surface light emitting structure, and at the same time, a light emitting layer And a method of manufacturing a multilayer inorganic electroluminescent device capable of simplifying the overall process and thus reducing costs by simultaneously forming a dielectric layer in a single process using spin coating, and a multilayer inorganic electroluminescent device manufactured therefrom. It is about.

Electroluminescence phenomenon has been actively applied in specific fields such as lighting and rear light source since it was discovered by Destriau in 1936, but its field of use has been very limited due to problems in brightness and lifespan. However, due to continuous research and technology development, the applicability in each field has been suggested. In particular, an inorganic electroluminescent device (hereinafter referred to as an inorganic EL device) having uniform planar light source, flexibility, light weight, and strong resistance to temperature change is proposed. Currently, it is actively used as a backlight element of a keypad for a mobile phone, and is used for various billboards, lighting, and vehicle mounting. In addition, unlike the thin film EL device or the hybrid EL device, the distributed inorganic EL device can be easily applied to a flexible substrate, can be enlarged, and all processes can be printed, thereby reducing costs. However, the inorganic EL device has a problem of lower luminance than other light sources.

Accordingly, there is a continuing need in the art for a method for manufacturing an inorganic EL device having a low cost and high luminance.

Embodiments of the present invention are to meet the above technical requirements, one technical problem to be achieved by the present invention is to simplify the overall process, while reducing the manufacturing cost, while increasing the luminance of the device multilayer multilayer inorganic electric field It is to provide a method of manufacturing a light emitting device.

Another object of the present invention is to provide a multi-layered inorganic electroluminescent device manufactured by the manufacturing method.

Aspect according to one embodiment of the present invention for achieving the above technical problem is

(a) forming a lower electrode on top of the substrate;

(b) simultaneously forming a light emitting layer and a dielectric layer on the lower electrode by spin coating;

(c) repeating steps (a) and (b) several times on top of the dielectric layer to form a plurality of composite layers including a lower electrode, a light emitting layer, and a dielectric layer;

(d) a method of manufacturing a multilayer inorganic electroluminescent device comprising forming a back electrode on an uppermost composite layer of the composite layer.

Aspects according to another embodiment of the present invention include a substrate, one or more composite layers on the substrate, and a back electrode on top of the top composite layer of the composite layers, each composite layer including a bottom electrode, a light emitting layer, and a dielectric layer. In addition, the light emitting layer and the dielectric layer relates to a multi-layered inorganic electroluminescent device is formed at the same time by the spin coating method on the lower electrode.

The present invention provides a method for manufacturing a multilayered inorganic electroluminescent device, characterized in that the light emitting layer and the dielectric layer are formed at the same time by spin coating, thereby simplifying the overall process and thereby reducing the cost, the production of the present invention The multi-layered inorganic electroluminescent device manufactured by the method is a multi-layer surface emitting structure including a plurality of light emitting layers, and the luminance is increased according to the number of light emitting layers at the same applied voltage, thereby exhibiting high luminance emission characteristics and simultaneously reducing voltage. Can bring

Hereinafter, exemplary embodiments will be described in more detail with reference to the accompanying drawings.

One aspect of the present invention

(a) forming a lower electrode on top of the substrate;

(b) simultaneously forming a light emitting layer and a dielectric layer on the lower electrode by spin coating;

(c) repeating steps (a) and (b) several times on top of the dielectric layer to form a plurality of composite layers including a lower electrode, a light emitting layer, and a dielectric layer;

(d) a method of manufacturing a multilayer inorganic electroluminescent device comprising forming a back electrode on an uppermost composite layer of the composite layers.

1 is a process flowchart of a method of manufacturing a multilayer inorganic electroluminescent device according to one embodiment of the present invention. Referring to FIG. 1, in the multilayer type inorganic electroluminescent device according to an embodiment of the present invention, a first lower electrode is formed on an upper portion of a substrate, and a light emitting layer and a dielectric layer are formed on the first lower electrode using spin coating. By forming a plurality of composite layers by repeating the same process on top of the composite layer including the lower electrode, the light emitting layer, and the dielectric layer, and then forming a rear electrode on the top of the composite layer. After formation, a multilayer inorganic EL element is manufactured by connecting each electrode to a driving power source.

That is, the manufacturing method of the present invention is characterized in that it comprises a plurality of light emitting layers by forming two or more composite layers including a lower electrode, a light emitting layer and a dielectric layer on top of the substrate, the light emitting layer and the dielectric layer of each composite layer By simultaneously forming a spin coating method on the lower electrode, it is possible to provide a low-cost light source by simplifying the manufacturing process by shortening the conventional light emitting layer and the dielectric layer in two steps. The lower electrode of each composite layer serves as a back electrode of another composite layer below the composite layer. Therefore, when the multi-layer electrode is manufactured in parallel connection to AC driving and voltage is applied, EL emission is emitted toward the transparent lower electrode or back electrode, and the luminance is increased according to the number of light emitting layers at the same applied voltage, thereby reducing the voltage. It can bring an effect.

The inorganic EL device manufactured by the manufacturing method of the present invention has a surface light emitting structure and EL is emitted in the direction of the lower electrode or the rear electrode. Therefore, one of the lower electrode and the bottom electrode should be a transparent electrode, the other one is preferably formed of a material having a high reflectance, and it is preferable that all the electrodes located therein are transparent electrodes. When the lower electrode is a transparent electrode, the substrate is also preferably transparent.

The lower electrode or the lower electrode used in the embodiments of the present invention as a material of the transparent electrode can be used without limitation conventionally used in the art, and is not particularly limited, metal oxides, conductive polymers, nanostructures and One or more selected from the group consisting of crystals may be appropriately selected and used depending on the intended use. As the metal oxide, at least one selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), InSnO, ZnO, SnO ₂ , NiO, and Cu ₂ SrO ₂ may be used. . Specific examples of the conductive polymer include polydiphenylacetylene, poly (t-butyl) diphenylacetylene, poly (trifluoromethyl) diphenylacetylene, poly (bistrifluoromethyl) acetylene, polybis (T-butyldi Phenyl) acetylene, poly (trimethylsilyl) diphenylacetylene, poly (carbazole) diphenylacetylene, polydiacetylene, polyphenylacetylene, polypyridineacetylene, polymethoxyphenylacetylene, polymethylphenylacetylene, poly (t-butyl) Phenylpolyacetylene polymers such as phenylacetylene, polynitrophenylacetylene, poly (trifluoromethyl) phenylacetylene, poly (trimethylsilyl) phenylacetylene, and derivatives thereof. Other available conductive polymers include polyaniline, polythiophene, polypyrole, polysilane, polystyrene, polyfuran, polyindole, polyazulene, polyphenylene, polypyridine, polybipyridine, poly Phthalocyanine, polyphenylene vinylene, polyethylenedioxythiophene (PEDOT) / polystyrenesulfonate (PSS) mixture, and derivatives thereof.

As the reflective electrode among the lower electrode or the back electrode of the present invention, a material commonly used may be used without limitation, and more specifically, a conductive metal or an oxide thereof, and specific examples thereof include nickel (Ni), platinum (Pt), Gold (Au), silver (Ag), iridium (Ir), aluminum (Al) and the like can be used.

In the manufacturing method according to an embodiment of the present invention, the lower electrode or the rear electrode may be formed by a method commonly used in the art, and is not particularly limited, and may be formed by, for example, a printing method or an etching method. Can be.

In the method of manufacturing the light emitting layer and the dielectric layer in the manufacturing method according to an embodiment of the present invention, the phosphor is mixed with an organic binder, and the light emitting layer and the dielectric layer are formed on the lower electrode by spin coating. When the spin coating method is used, relatively heavy phosphor particles are aligned downward to form a light emitting layer, and an organic binder is formed on the phosphor while surrounding the phosphor to form a dielectric layer, thereby forming a light emitting layer and a dielectric layer at the same time.

In the present invention, the organic binder takes the place of the dielectric layer of the conventional inorganic electroluminescent device. The role of the dielectric layer is to provide electrons to the light emitting layer through a high voltage applied from the outside, and serves to prevent breakdown of the device itself with respect to the high voltage applied thereto. Therefore, it is preferable to use a material having a high dielectric constant as the organic binder used in the method of manufacturing the multilayer inorganic electroluminescent device of the present invention.

In the manufacturing method according to an embodiment of the present invention, the mixing ratio of the phosphor and the organic binder is preferably 1: 1 to 1: 7 based on the mass ratio. More preferably, it is 1: 2.

In the embodiments of the present invention, as the phosphor used as the light emitting layer material, a host material doped with an active material for determining color may be used. The host material corresponding to the matrix of the phosphor is preferably a material having a large band gap, and may be excited in a high field and preferably have a lattice capable of receiving an active material that emits visible light. As the host material, compounds consisting of Groups 12-16, 13-15, and 14-14 of the Periodic Table and mixtures thereof may be used, and may be appropriately selected according to the emission wavelength. For example, ZnS, ZnSe, GaAs, GaAlAs, GaAsP, AlGalnP, AlAs, GaP, AIP, SiC, GaN, GaInN, GaAlN, or a combination thereof may be used, but is not limited thereto.

More specifically, examples of the phosphors used in the embodiments of the present invention include ZnS: Cu, ZnS: Cu, Mn, Cl, ZnS: Sm, F, ZnS: SM, Cl, CaS: Eu which emit red light. ZnS: Cu, Al, ZnS: Tb, F, CaS: Ce, emitting green, ZnS: Tm, F, SrS: Ce, ZnS / SrS: Ce, CaGa ₂ S ₄ : Ce ZnS: Cu , Cl, ZnS: Cu, I, and other ZnS: Mn phosphors emitting yellow light may be used, but is not limited thereto.

The organic binder used in the embodiments of the present invention preferably has a high dielectric constant, and includes, for example, cyanoylated cellulose resin such as cyanoethyl cellulose resin, cyanoethyl pullulan resin, and the like. One or more resins selected from the group consisting of cyanoylated fluorane resin, vinylidene fluoride rubber, vinylidene fluoride copolymer rubber resin, cyanoylated polyvinyl alcohol, and the like may be used, but is not limited thereto.

Another embodiment of the present invention includes a substrate, at least one composite layer on the substrate, and a rear electrode on top of the composite layer, wherein each of the composite layers includes a lower electrode, a light emitting layer, and a dielectric layer. The light emitting layer and the dielectric layer are related to a multilayer type inorganic electroluminescent device which is simultaneously formed on the lower electrode by spin coating.

2 is a schematic cross-sectional view of a multilayer inorganic electroluminescent device manufactured according to one embodiment of the present invention. More specifically, referring to FIG. 2, the structure of the multilayered inorganic electroluminescent device of the present invention includes a substrate 21, a lower electrode 22, a light emitting layer 23, and a dielectric layer 24 of the upper substrate 21. A plurality of composite layers 25 and back electrodes 26 are included. That is, as a multi-layer surface emitting structure including a plurality of light emitting layers, in the multilayer inorganic electroluminescent device of the present invention, the lower electrode of each composite layer serves as a back electrode of another composite layer under the composite layer. Therefore, when a voltage is applied to a plurality of electrodes connected to the driving power source, a current flows to the phosphor in the light emitting layer, and the phosphor emits light, and the light is emitted toward the transparent lower electrode or the back electrode, thereby exhibiting higher luminance than the inorganic EL element of a single layer. . In addition, by simultaneously mixing the phosphor and the organic binder to form the light emitting layer 23 and the dielectric layer 24 by the spin coating method, as the contact interface between the phosphor and the organic binder increases, the luminance of the entire element is increased to the conventional inorganic EL element. Increased compared to. In addition, when a plurality of electrodes are connected in parallel to a driving power source, a plurality of light emitting layers emit light at the same applied voltage, thereby reducing the voltage.

The multi-layered inorganic electroluminescent device according to the present invention exhibits flexible device characteristics by using a flexible organic material together with high luminance emission characteristics, and thus can be applied to a flexible light source such as a display device or an optical printer using the same.

The substrate used for the multilayered inorganic electroluminescent device of the present invention is not particularly limited as long as the purpose is not impaired. For example, silica, glass, plastic, and the like can be appropriately selected and used by those skilled in the art according to the use. However, in a structure in which light is emitted toward the lower electrode, it is preferable to use a transparent substrate. The thickness of the substrate can be appropriately selected and used by those skilled in the art according to the use.

It is preferable that any one of the lower electrode and the back electrode of the present invention is a transparent electrode, the other one is preferably formed of a material having high reflectance, and the internal electrodes are all transparent electrodes. As the transparent electrode of the lower electrode or the back electrode of the present invention, those commonly used in the art may be used without limitation, and are not particularly limited, but may be selected from the group consisting of metal oxides, conductive polymers, nanostructures, and crystals. One or more types can be appropriately selected and used depending on the intended use. As the metal oxide, at least one selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), InSnO, ZnO, SnO ₂ , NiO, and Cu ₂ SrO ₂ may be used. . Specific examples of the conductive polymer include polydiphenylacetylene, poly (t-butyl) diphenylacetylene, poly (trifluoromethyl) diphenylacetylene, poly (bistrifluoromethyl) acetylene, polybis (T-butyldi Phenyl) acetylene, poly (trimethylsilyl) diphenylacetylene, poly (carbazole) diphenylacetylene, polydiacetylene, polyphenylacetylene, polypyridineacetylene, polymethoxyphenylacetylene, polymethylphenylacetylene, poly (t- Phenylpolyacetylene polymers such as butyl) phenylacetylene, polynitrophenylacetylene, poly (trifluoromethyl) phenylacetylene, poly (trimethylsilyl) phenylacetylene, and derivatives thereof. Other available conductive polymers include polyaniline, polythiophene, polypyrole, polysilane, polystyrene, polyfuran, polyindole, polyazulene, polyphenylene, polypyridine, polybipyridine, poly Phthalocyanine, polyphenylene vinylene, polyethylenedioxythiophene (PEDOT) / polystyrenesulfonate (PSS) mixture, and derivatives thereof.

As the reflective electrode among the lower electrode or the back electrode of the present invention, a material commonly used may be used without limitation, and more specifically, a conductive metal or an oxide thereof, and specific examples thereof include nickel (Ni), platinum (Pt), Gold (Au), silver (Ag), iridium (Ir), aluminum (Al) and the like can be used.

As the phosphor included in the emission layer of the present invention, a host material doped with an activator for determining color may be used. The host material corresponding to the matrix of the phosphor is preferably a material having a large band gap, and may be excited in a high field and preferably have a lattice capable of receiving an active material that emits visible light. As the host material, compounds consisting of Groups 12-16, 13-15, and 14-14 of the Periodic Table and mixtures thereof may be used, and may be appropriately selected according to the emission wavelength. For example, ZnS, ZnSe, GaAs, GaAlAs, GaAsP, AlGalnP, AlAs, GaP, AIP, SiC, GaN, GaInN, GaAlN, or a combination thereof may be used, but is not limited thereto.

More specifically, examples of the phosphors used in the embodiments of the present invention include ZnS: Cu, ZnS: Cu, Mn, Cl, ZnS: Sm, F, ZnS: SM, Cl, CaS: Eu which emit red light. ZnS: Cu, Al, ZnS: Tb, F, CaS: Ce, emitting green, ZnS: Tm, F, SrS: Ce, ZnS / SrS: Ce, CaGa ₂ S ₄ : Ce ZnS: Cu , Cl, ZnS: Cu, I, and other ZnS: Mn phosphors emitting yellow light may be used, but is not limited thereto.

The organic binder included in the dielectric layer of the present invention preferably has a high dielectric constant, and may be, for example, cyanoylated cellulose resin such as cyanoethyl cellulose resin, cyanoethyl pullulan resin, or the like. One or more resins selected from the group consisting of pullulan resin, vinylidene fluoride rubber, vinylidene fluoride copolymer rubber resin, cyanoylated polyvinyl alcohol, and the like may be used, but is not limited thereto.

Hereinafter, the preferred embodiments of the present invention will be described in more detail with reference to Examples and the like, but these Examples are only for the purpose of description and should not be construed as limiting the protection scope of the present invention.

Example  One

ITO was applied on a 1.8 mm thick soda lime glass substrate by sputtering to form a 2000 A thick lower electrode, and 5 g of ZnS: Cu, Cl phosphors were mixed with 10 g of fluoro resin, which was then spun. The coating was applied at a thickness of 15 um on the lower electrode at 1000 rpm and then dried at 130 ° C. for 30 minutes. Subsequently, as shown in FIG. 3, ITO is applied to a part of the area of the lower layer by sputtering to form a lower electrode having a thickness of 2000 A, and 5 g of ZnS: Cu, Cl phosphor is mixed with 10 g of fluorine resin, which is spin coated. After applying a thickness of 15 um on the upper lower electrode at 1000 rpm and dried for 30 minutes at 130 ℃. Thereafter, a back electrode having a thickness of 2000 A was formed on the upper portion of the device by a sputtering method to prepare two layers of inorganic EL devices.

Example  2

In Preparation Example 1, a three-layer inorganic EL device was manufactured by performing the process of forming a composite layer including a lower electrode, a light emitting layer, and a dielectric layer once more. At this time, each composite layer was prepared to be reduced in area as it goes up as shown in FIG.

Experimental Example  One

The emission pictures of the inorganic EL devices fabricated in Examples 1 and 2 are shown in FIGS. 3 and 4, and the luminances of the inorganic EL devices are measured and shown in FIGS. 5 and 6. Voltage and current applied by connecting a plurality of lower and rear electrodes were measured with an oscilloscope (Agilent, infiniium oscilloscope) and luminance was measured with a luminance colorimeter (TOPCON, BM-7).

Referring to FIG. 3, in the inorganic EL device including two light emitting layers, the luminance when the driving voltage is applied to both layers is higher than that when the driving voltage is applied only to the lower layer or the upper layer. 5, there is almost no difference in luminance between layers under the same voltage, and it can be seen that the luminance when driving both layers represents the sum of the luminance when driving each layer separately.

Referring to FIG. 4, it can be seen that in the inorganic EL device including three light emitting layers, the luminance is higher when the driving voltage is applied to all three layers than when the driving voltage is applied only to a single layer or two layers. FIG. 6 is a graph comparing the luminance of each element, and it can be seen that the luminance of the device increases in proportion to the number of layers under the same voltage.

Referring to this, it can be seen that the multilayer inorganic EL device manufactured according to the manufacturing method of the present invention exhibits excellent luminance.

Although the present invention has been described in detail with reference to preferred embodiments of the present invention, these are merely exemplary, and those skilled in the art to which the present invention pertains have various modifications and equivalents therefrom. It will be appreciated that embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a process flow diagram of a method of manufacturing a multilayer inorganic electroluminescent device according to one embodiment of the present invention,

2 is a schematic cross-sectional view of a multilayer inorganic electroluminescent device manufactured according to one embodiment of the present invention,

3 is a light-emitting photograph of the EL device obtained in Example 1 of the present invention,

4 is a light-emitting photograph of the EL device obtained in Example 2 of the present invention,

5 is a graph showing luminance according to an applied voltage of an EL device obtained in Example 1 of the present invention.

6 is a graph showing luminance according to an applied voltage of an EL element obtained in Example 2 of the present invention.

* Description of the symbols for the main parts of the drawings *

21 substrate 22 lower electrode

23: light emitting layer 24: dielectric layer

25: composite layer 26: back electrode

Claims (10)

(a) forming a lower electrode on top of the substrate; (b) simultaneously forming a light emitting layer and a dielectric layer on the lower electrode by spin coating; (c) repeating steps (a) and (b) several times on top of the dielectric layer to form a plurality of composite layers including a lower electrode, a light emitting layer, and a dielectric layer; (d) forming a back electrode on an uppermost composite layer of the composite layer. The method of claim 1, wherein the light emitting layer and the dielectric layer forming step are formed by mixing a phosphor with an organic binder and spin coating the lower electrode. The method of claim 2, wherein the mixing ratio of the phosphor and the organic binder is 1: 1 to 1: 7 based on the mass ratio. The method of claim 2, wherein the phosphor is ZnS: Cu, ZnS: Mn, SrS: Ce, ZnS: Cu, Mn, Cl, ZnS: Cu, Al, ZnS: Cu, Cl, ZnS: Cu, I, ZnS: Sm, F, ZnS: SM, Cl, CaS: Eu, ZnS: Tb, F, CaS: Ce, ZnS: Tm, F, SrS: Ce, ZnS / SrS: Ce, CaGa ₂ S ₄ : Ce and a method of manufacturing a multilayer inorganic electroluminescent device, characterized in that at least one selected from the group consisting of a combination thereof. The method of manufacturing a multilayer inorganic electroluminescent device according to claim 2, wherein the organic binder is a high dielectric resin. The organic binder of claim 2, wherein the organic binder is at least one resin selected from the group consisting of cyanoylated cellulose resin, cyanoylated fluorane resin, vinylidene fluoride rubber, vinylidene fluoride copolymer rubber resin, and polyvinylated polyvinyl alcohol. Method for producing a multilayer inorganic electroluminescent device, characterized in that at least one selected from the group consisting of. A substrate, one or more composite layers over the substrate, and a back electrode over the top of the composite layers, each composite layer including a bottom electrode, a light emitting layer, and a dielectric layer, wherein the light emitting layer and the dielectric layer are the bottom A multi-layered inorganic electroluminescent device formed simultaneously on the electrode by spin coating. The method of claim 7, wherein the light emitting layer is ZnS: Cu, ZnS: Mn, SrS: Ce, ZnS: Cu, Mn, Cl, ZnS: Cu, Al, ZnS: Cu, Cl, ZnS: Cu, I, ZnS: Sm, F, ZnS: SM, Cl, CaS: Eu, ZnS: Tb, F, CaS: A multi-layered inorganic electroluminescent device comprising at least one selected from the group consisting of Ce, ZnS: Tm, F, SrS: Ce, ZnS / SrS: Ce, CaGa ₂ S ₄ : Ce, and combinations thereof. The method of claim 7, wherein the dielectric layer is made of at least one resin selected from the group consisting of cyanoylated cellulose resin, cyanoylated fluorane resin, vinylidene fluoride rubber, vinylidene fluoride copolymer rubber resin, and cyanoylated polyvinyl alcohol. Multi-layered inorganic electroluminescent device comprising at least one selected from the group. The multi-layered inorganic electroluminescent device of claim 7, wherein the multi-layered inorganic electroluminescent device is connected in parallel to all electrodes in one driving power source.

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